Polyisobutylenes and process for making same

ABSTRACT

The present invention generally relates to alcohol-terminated polyisobutylene (PIB) compounds, and to a process for making such compounds. In one embodiment, the present invention relates to primary alcohol-terminated polyisobutylene compounds, and to a process for making such compounds. In still another embodiment, the present invention relates to polyisobutylene compounds that can be used to synthesize polyurethanes, to polyurethane compounds made via the use of such polyisobutylene compounds, and to processes for making such compounds. In yet another embodiment, the present invention relates to primary alcohol-terminated polyisobutylene compounds having two or more primary alcohol termini and to a process for making such compounds. In yet another embodiment, the present invention relates to primary terminated polyisobutylene compounds having two or more primary termini selected from amine groups or methacrylate groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 12/516,270, filed Jan. 20, 2010, pending, which is a 371national phase filing of International Application No.PCT/US2007/024674, filed Nov. 30, 2007, which claims the benefit of bothU.S. Provisional Patent Application No. 60/959,065, filed Jul. 11, 2007,and U.S. Provisional Patent Application No. 60/861,802, filed Nov. 30,2006, all of the disclosures of which are incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The present invention was made in the course of research that wassupported by National Science Foundation (NSF) Grant DMR 02-43314-3. TheUnited States government may have certain rights to the invention orinventions herein.

FIELD OF THE INVENTION

The present invention generally relates to alcohol-terminatedpolyisobutylene (PIB) compounds, and to a process for making suchcompounds. In one embodiment, the present invention relates to primaryalcohol-terminated polyisobutylene compounds, and to a process formaking such compounds. In still another embodiment, the presentinvention relates to polyisobutylene compounds that can be used tosynthesize polyurethanes, to polyurethane compounds made via the use ofsuch polyisobutylene compounds, and to processes for making suchcompounds. In yet another embodiment, the present invention relates toprimary alcohol-terminated polyisobutylene compounds having two or moreprimary alcohol termini and to a process for making such compounds. Inyet another embodiment, the present invention relates to primaryterminated polyisobutylene compounds having two or more primary terminiselected from amine groups or methacrylate groups.

BACKGROUND OF THE INVENTION

Various polyurethanes (PUs) are multibillion dollar commodities and aremanufactured worldwide by some of the largest chemical companies (e.g.,Dow, DuPont, BASF, and Mitsui). Polyurethanes are used in a wide varietyof industrial and clinical applications in the form of, for example,thermoplastics, rubbers, foams, upholstery, tubing, and variousbiomaterials.

Typically, PUs are made by combining three ingredients: (1) a diol (suchas tetramethylene oxide); (2) a diisocyanate (such as 4,4′-methylenediphenyl diisocyanate); and (3) an extender (such as 1,4-butane diol).Generally, polyurethanes (Pus) contain a soft (rubbery) and a hard(crystalline) component; and the properties of PUs depend on the natureand relative concentration of the soft/hard components.

Even though primary alcohol-terminated PIB compounds, such asHOCH₂—PIB-CH₂OH, have been prepared in the past previous synthesismethods have been uneconomical. As such, the cost of manufacturingprimary alcohol-terminated PIB compounds has been too high forcommercial production. One reason for the high cost associated withmanufacturing primary alcohol-terminated PIB compounds, such asHOCH₂-PIB-CH₂OH, is that the introduction of a terminal CH₂OH group atthe end of the PIB molecule necessitates the use of thehydroboration/oxidation method a method that requires the use ofexpensive boron chemicals (H₆B₂ and its complexes).

Given the above, numerous efforts have been made to develop aneconomical process for manufacturing primary alcohol-terminated PIBcompounds, such as HOCH₂-PIB-CH₂OH. For example, BASF has spent millionsof dollars on the research and development of a process to makeHOCH₂-PIB-CH₂OH by hydroboration/oxidation, where such a processpermitted the recovery and reuse of the expensive boron containingcompounds used therein. Other research efforts have been made, and havemet with limited success in reducing the cost associated with producingprimary alcohol-terminated PIB compounds, such as PIB-CH₂OH orHOCH₂-PIB-CH₂OH.

With regard to amine-terminated PIBs, early efforts directed toward thesynthesis of amine-terminated telechelic PIBs were both cumbersome andexpensive, and the final structures of the amine-telechelic PIBs aredifferent from those described below.

More recently, Binder et al. (see, e.g., D. Machl, M. J. Kunz and W. H.Binder, Polymer Preprints, 2003, 44(2), p. 85) initiated the livingpolymerization of isobutylene under well-known conditions, terminatedthe polymer with 1-(3-bromopropyl)-4-(1-phenylvinyl)-benzene, andeffected a complicated series of reactions on the product to obtainamine-terminated PIBs. Complex structures very different from thosedisclosed herein were obtained and the above method did not yieldamine-terminated telechelic PIB compounds that carry 1.0±0.05 functionalgroups.

Given the above, there is a need in the art for a manufacturing processthat permits the efficient and cost-effective production/manufacture ofprimary alcohol-terminated PIB compounds, primary amine-terminated PIBcompounds, primary methacrylate-terminated PIB compounds, and/or primaryamine-terminated telechelic PIB compounds.

SUMMARY OF THE INVENTION

The present invention generally relates to alcohol-terminatedpolyisobutylene (PIB) compounds, and to a process for making suchcompounds. In one embodiment, the present invention relates to primaryalcohol-terminated polyisobutylene compounds, and to a process formaking such compounds. In still another embodiment, the presentinvention relates to polyisobutylene compounds that can be used tosynthesize polyurethanes, to polyurethane compounds made via the use ofsuch polyisobutylene compounds, and to processes for making suchcompounds. In yet another embodiment, the present invention relates toprimary alcohol-terminated polyisobutylene compounds having two or moreprimary alcohol termini and to a process for making such compounds. Inyet another embodiment, the present invention relates to primaryterminated polyisobutylene compounds having two or more primary terminiselected from amine groups or methacrylate groups.

In one embodiment, the present invention relates to a method forproducing a primary alcohol-terminated polyisobutylene compoundcomprising the steps of: (A) providing an alkenyl-terminatedpolyisobutylene having at least two alkenyl termini, wherein the alkenyltermini are formed from straight or branched C₃ to C₁₂ alkenyl groupshaving a double bond present at the end of the alkenyl group; (B)subjecting the alkenyl-terminated polyisobutylene to anti-Markovnikovbromination to form a primary bromine-terminated polyisobutylenecompound having at least two primary bromine termini; (C) converting theprimary bromine-terminated polyisobutylene compound to a primaryalcohol-terminated polyisobutylene via a base reaction, the primaryalcohol-terminated polyisobutylene having at least two primary alcoholtermini; and (D) recovering the primary alcohol-terminatedpolyisobutylene.

In another embodiment, the present invention relates to a primaryalcohol-terminated polyisobutylene compound according to the followingformula:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—R—OH

where ˜˜˜ represents the remaining portion of a linear, star,hyperbranched, or arborescent molecule, n is an integer from 2 to about5,000, and R is a straight or branched C₃ to C₁₂ linkage formed from acorresponding straight or branched C₃ to C₁₂ alkenyl group having adouble bond present at the end of the alkenyl group, and where theprimary alcohol-terminated polyisobutylene has at least two primaryalcohol termini.

In still another embodiment, the present invention relates to a methodfor producing a primary methacrylate-terminated polyisobutylene compoundcomprising the steps of: (a) providing an alkenyl-terminatedpolyisobutylene having at least two alkenyl termini, wherein the alkenyltermini are formed from straight or branched C₃ to C₁₂ alkenyl groupshaving a double bond present at the end of the alkenyl group; (b)subjecting the alkenyl-terminated polyisobutylene to anti-Markovnikovbromination to form a primary bromine-terminated polyisobutylenecompound having at least two primary bromine termini; (c) converting theprimary bromine-terminated polyisobutylene compound to a primarymethacrylate-terminated polyisobutylene via a reaction with at least onealkaline methacrylate compound, the primary methacrylate-terminatedpolyisobutylene having at least two primary methacrylate termini; and(d) recovering the primary methacrylate-terminated polyisobutylene.

In still yet another embodiment, the present invention relates to aprimary methacrylate-terminated polyisobutylene compound according tothe following formula:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—R-Ma

where ˜˜˜ represents the remaining portion of a linear, star,hyperbranched, or arborescent molecule, n is an integer from 2 to about5,000, R is a straight or branched C₃ to C₁₂ linkage formed from acorresponding straight or branched C₃ to C₁₂ alkenyl group having adouble bond present at the end of the alkenyl group, and Ma represents amethacrylate termini, and where the primary methacrylate-terminatedpolyisobutylene has at least two primary methacrylate termini.

In still yet another embodiment, the present invention relates to amethod for producing a primary amine-terminated polyisobutylene compoundcomprising the steps of: (i) providing an alkenyl-terminatedpolyisobutylene having at least two alkenyl termini, wherein the alkenyltermini are formed from straight or branched C₃ to C₁₂ alkenyl groupshaving a double bond present at the end of the alkenyl group; (ii)subjecting the alkenyl-terminated polyisobutylene to anti-Markovnikovbromination to form a primary bromine-terminated polyisobutylenecompound having at least two primary bromine termini; (iii) convertingthe primary bromine-terminated polyisobutylene compound to a primaryphthalimide-terminated polyisobutylene via a reaction with at least onealkaline phthalimide compound, the primary phthalimide-terminatedpolyisobutylene having at least two primary phthalimide termini; (iv)converting the primary phthalimide-terminated polyisobutylene compoundto a primary amine-terminated compound via a reaction with an aminehydrate compound; and (v) recovering the primary amine-terminatedpolyisobutylene.

In still yet another embodiment, the present invention relates to aprimary amine-terminated polyisobutylene compound according to thefollowing formula:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—R—NH₂

where ˜˜˜ represents the remaining portion of a linear, star,hyperbranched, or arborescent molecule, n is an integer from 2 to about5,000, and R is a straight or branched C₃ to C₁₂ linkage formed from acorresponding straight or branched C₃ to C₁₂ alkenyl group having adouble bond present at the end of the alkenyl group, and where theprimary amine-terminated polyisobutylene has at least two primarymethacrylate termini.

In still yet another embodiment, the present invention relates to amethod for producing a primary bromine-terminated polyisobutylenecompound comprising the steps of: providing an alkenyl-terminatedpolyisobutylene having at least two alkenyl termini, wherein the alkenyltermini are formed from straight or branched C₃ to C₁₂ alkenyl groupshaving a double bond present at the end of the alkenyl group; subjectingthe alkenyl-terminated polyisobutylene to anti-Markovnikov brominationto form a primary bromine-terminated polyisobutylene compound having atleast two primary bromine termini; and recovering the primarybromine-terminated polyisobutylene.

In still yet another embodiment, the present invention relates to aprimary bromine-terminated polyisobutylene compound according to thefollowing formula:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—R—Br

where ˜˜˜ represents the remaining portion of a linear, star,hyperbranched, or arborescent molecule, n is an integer from 2 to about5,000, and R is a straight or branched C₃ to C₁₂ linkage formed from acorresponding straight or branched C₃ to C₁₂ alkenyl group having adouble bond present at the end of the alkenyl group, and where theprimary bromine-terminated polyisobutylene has at least two primarybromine termini.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a ¹H NMR spectrum of a three-arm star PIB molecule where thearm segments are-terminated with allyl groups (Ø(PIB-Allyl)₃);

FIG. 1B is a ¹H NMR spectrum of a three-arm star PIB molecule where thearm segments are-terminated with primary bromines (—CH₂—Br);

FIG. 2 is a ¹H NMR spectrum of phthalimide-telechelic polyisobutylene;and

FIG. 3 is a ¹H NMR spectrum of amine-telechelic polyisobutylene.

DETAILED DESCRIPTION OF THE INVENTION

The present invention generally relates to alcohol-terminatedpolyisobutylene (PIB) compounds, and to a process for making suchcompounds. In one embodiment, the present invention relates to primaryalcohol-terminated polyisobutylene compounds, and to a process formaking such compounds. In still another embodiment, the presentinvention relates to polyisobutylene compounds that can be used tosynthesize polyurethanes, to polyurethane compounds made via the use ofsuch polyisobutylene compounds, and to processes for making suchcompounds. In yet another embodiment, the present invention relates toprimary alcohol-terminated polyisobutylene compounds having two or moreprimary alcohol termini and to a process for making such compounds. Inyet another embodiment, the present invention relates to primaryterminated polyisobutylene compounds having two or more primary terminiselected from amine groups or methacrylate groups.

Although the present invention specifically discloses a method forproducing various PIB molecules-terminated with one —CH₂—CH₂—CH₂—OHgroup, the present invention is not limited thereto. Rather, the presentinvention can be used to produce a wide variety of PIB moleculargeometries, where such molecules are-terminated with one or more primaryalcohols.

In one embodiment, the primary alcohols that can be used as terminatinggroups in the present invention include, but are not limited to, anystraight or branched chain primary alcohol substituent group having from1 to about 12 carbon atoms, or from 1 to about 10 carbon atoms, or from1 to about 8, or from about 1 to about 6 carbon atoms, or even fromabout 2 to about 5 carbon atoms. Here, as well as elsewhere in thespecification and claims, individual range limits can be combined toform alternative non-disclosed range limits.

In one embodiment, the present invention relates to linear, orstar-shaped, or hyperbranched, or arborescent PIB compounds, where suchcompounds contain one or more primary alcohol-terminated segments. Suchmolecular geometries are known in the art, and a discussion herein isomitted for the sake of brevity. In another embodiment, the presentinvention relates to star-shaped molecules that contain a center cyclicgroup (e.g., an aromatic group) to which three or more primaryalcohol-terminated PIB arms are attached.

The following examples are exemplary in nature and the present inventionis not limited thereto. Rather, as is noted above, the present inventionrelates to the production and/or manufacture of various PIB compoundsand polyurethane compounds made therefrom.

EXAMPLES

The following example concerns the synthesis of a primaryhydroxyl-terminated polyisobutylene in three steps:

1. Preparation of a Star Molecule with Three Allyl-Terminated PIB Arms(Ø(PIB-Allyl)₃)

The synthesis of Ø(PIB-Allyl)₃ followed the procedure described by LechWilczek and Joseph P. Kennedy in The Journal of Polymer Science: Part A:Polymer Chemistry, 25, pp. 3255 through 3265 (1987), the disclosure ofwhich is incorporated by reference herein in its entirety.

The first step involves the polymerization of isobutylene totert-chlorine-terminated PIB by the1,3,5-tri(2-methoxyisopropyl)benzene/TiCl₄ system under a blanket of N₂in a dry-box. Next, in a 500 mL three-neck round bottom glass flask,equipped with an overhead stirrer, the following are added: a mixedsolvent (n-hexane/methyl chloride, 60/40 v/v), 2,6-di-t-butyl pyridine(0.007 M), 1,3,5-tri(2-methoxyisopropyl)benzene (0.044M), andisobutylene (2 M) at a temperature of −76° C. Polymerization is inducedby the rapid addition of TiCl₄ (0.15 M) to the stirred charge. After 10minutes of stirring the reaction is terminated by the addition of a 3fold molar excess of allyltrimethylsilane (AllylSiMe₃) relative to thetert-chlorine end groups of the Ø(PIB-Cl)₃ that formed. After 60 minutesof further stirring at −76° C., the system is deactivated by introducinga few milliliters of aqueous NaHCO₃, and the (allyl-terminatedpolyisobutylene) product is isolated. The yield is 28 grams (85% oftheoretical); M_(n)=3000 g/mol.

2. Preparation of Ø(PIB-CH₂—CH₂—CH₂—Br)₃: Anti-Markovnikov Addition ofHBr to Ø(PIB-Allyl)₃

A 100 mL three-neck flask is charged with heptane (50 mL) andallyl-telechelic polyisobutylene (10 grams), and air is bubbled throughthe solution for 30 minutes at 100° C. to activate the allylic endgroups. Then the solution is cooled to approximately −10° C. and HBr gasis bubbled through the system for 10 minutes.

Dry HBr is generated by the reaction of aqueous (47%) hydrogen bromideand sulfuric acid (95 to 98%). After neutralizing the solution withaqueous NaHCO₃ (10%), the product is washed 3 times with water. Finallythe solution is dried over magnesium sulfate for at least 12 hours(i.e., over night) and filtered. The solvent is then removed via arotary evaporator. The product is a clear viscous liquid.

FIG. 1A shows the ¹H NMR spectrum of the allyl-terminated PIB and theprimary bromine-terminated PIB product (FIG. 1B). The formulae and thegroup assignments are indicated below for FIGS. 1A and 1B.

where n is an integer from 2 to about 5,000, or from about 7 to about4,500, or from about 10 to about 4,000, or from about 15 to about 3,500,or from about 25 to about 3,000, or from about 75 to about 2,500, orfrom about 100 to about 2,000, or from about 250 to about 1,500, or evenfrom about 500 to about 1,000. Here, as well as elsewhere in thespecification and claims, individual range limits can be combined toform alternative non-disclosed range limits.

It should be noted that the present invention is not limited to solelythe use of allyl-terminated compounds, shown above, in thealcohol-terminated polyisobutylene production process disclosed herein.Instead, other straight or branched C₃ to C₁₂, C₄ to C₁₀, or even C₅ toC₇ alkenyl groups can be used so long as one double bond in such alkenylgroups is present at the end of the chain. Here, as well as elsewhere inthe specification and claims, individual range limits can be combined toform alternative non-disclosed range limits.

As a further example regarding the above-mentioned alkenyl groups thefollowing general formula is used to show the positioning of the enddouble bond:—R₁═CH₂where R₁ is the remaining portion of the straight or branched alkenylgroups described above. In another embodiment, the alkenyl groups of thepresent invention contain only one double bond and this double bond isat the end of the chain as described above.

The olefinic (allylic) protons at 5 ppm present in spectrum (A)completely disappear upon anti-Markovnikov hydrobromination, as is shownin spectrum (B). The aromatic protons present in the1,3,5-tri(2-methoxyisopropyl)benzene (initiator residue) provide aninternal reference. Thus, integration of the terminal methylene protonsof the -PIB-CH₂—CH₂—CH ₂—Br relative to the three aromatic protons inthe initiator fragment yields quantitative functionality information.The complete absence of allyl groups and/or secondary bromines indicatessubstantially 100% conversion to the target anti-Markovnikov productØ-(PIB-CH₂—CH₂—CH₂—Br)₃.

3. Preparation of Ø(PIB-CH₂—CH₂—CH₂—OH)₃ from Ø-(PIB-CH₂—CH₂—CH₂—Br₃)

The conversion of the terminal bromine product to a terminal primaryhydroxyl group is performed by nucleophilic substitution on the bromine.A round bottom flask equipped with a stirrer is charged with a solutionof Ø(PIB-CH₂—CH₂—CH₂—Br)₃ in THF. Then an aqueous solution of NaOH isadded, and the charge is stirred for 2 hours at room temperature.Optionally, a phase transfer catalyst such as tetraethyl ammoniumbromide can be added to speed up the reaction. The product is thenwashed 3 times with water, dried over magnesium sulfate overnight andfiltered. Finally the solvent is removed via the use of a rotaryevaporator. The product, a primary alcohol-terminated PIB product, is aclear viscous liquid.

In another embodiment, the present invention relates to a process forproducing halogen-terminated PIBs (e.g., chlorine-terminated PIBs ratherthan the bromine containing compounds discussed above). Thesehalogen-terminated PIBs can also be utilized in above process andconverted to primary alcohol-terminated PIB compounds. Additionally, asis noted above, the present invention relates to the use of such PIBcompounds in the production of polyurethanes, as well as a variety ofother polymeric end products, such as methacrylates (via a reaction withmethacryloyl chloride), hydrophobic adhesives (e.g., cyanoacrylatederivatives), epoxy resins, polyesters, etc.

In still another embodiment, the primary halogen-terminated PIBcompounds of the present invention can be converted into PIB compoundsthat contain end epoxy groups, amine groups, etc. Previous efforts toinexpensively prepare primary halogen-terminated PIB compounds werefruitless and only resulted in compounds with tertiary terminalhalogens.

As noted above, the primary alcohol-terminated PIBs are usefulintermediates in the preparation of polyurethanes by reaction viaconventional techniques, i.e., by the use of known isocyanates (e.g.,4,4′-methylenediphenyl diisocyanate, MDI) and chain extension agents(e.g., 1,4-butane diol, BDO). The great advantage of these polyurethanes(PUs) is their biostability imparted by the biostable PIB segment.Moreover, since PIB is known to be biocompatible, any PU made from thePIB compounds of the present invention is novel as well asbiocompatible.

The primary terminal OH groups can be further derivatized to yieldadditional useful derivatives. For example, they can be converted toterminal cyanoacrylate groups which can be attached to living tissue andin this manner new tissue adhesives can be prepared.

In one embodiment of the present invention, the starting PIB segment canbe mono-, di- tri, and multi-functional, and in this manner one canprepare di-terminal, tri-terminal, or other PIB derivatives. In anotherembodiment, the present invention makes it possible to prepare α,ωdi-terminal (telechelic), tri-terminal, or other PIB derivatives. One ofthe most interesting PIB starting materials is arborescent-PIB (arb-PIB)that can carry many primary halogen termini, all of which can beconverted to primary alcohol groups.

In another embodiment, the following equations describe furtherprocesses and compounds that can be produced via the present invention.As a general rule, all of the following reactions can be run at a 95% orbetter conversion rate.

(A) Cationic living isobutylene polymerization affords a firstintermediate which is, for example, a tert-Cl— terminated PIB chain:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—C(CH₃)₂—Cl  (A)where ˜˜˜ represents the remaining portion of a linear, star,hyperbranched, or arborescent molecule and n is defined as noted above.As would be apparent to those of skill in the art, ˜˜˜ can in someinstances represent another chlorine atom in order to permit theproduction of substantially linear di-terminal primary alcohol PIBs.Additionally, it should be noted that the present invention is notlimited to the above specific linking groups (i.e., the —C(CH₃)₂)between the repeating PIB units and the remainder of the molecules ofthe present invention.

(B) The next step is the dehydrogenation of (A) to afford the secondintermediate shown below:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—C(CH₃)═CH₂  (B).

(C) The third step is the anti-Markovnikov bromination of (B) to affordthe primary bromide shown below:˜˜˜C(CH₃)₂—[CH₂C(CH₃)₂]_(n)—CH₂—CH(CH₃)CH₂—Br  (C).

(D) The fourth step is the conversion of the primary bromide by the useof a base (e.g., NaOH, KOH, or tert-BuONa) to a primary hydroxyl groupaccording to the following formula:˜˜˜C(CH₃)₂—[CH₂C(CH₃)₂]_(n)—CH₂—CH(CH₃)—CH₂—OH  (D).

In another embodiment, the following reaction steps can be used toproduce a primary alcohol-terminated PIB compound according to thepresent invention.

(B′) Instead of the dehydrogenation, as outlined in (B), one can use anallyl silane such as trimethyl allyl silane to prepare an allylterminated PIB:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—CH═CH₂  (B′).

(C′) Similarly to the reaction shown in (C) above, the (B′) intermediateis converted to the primary bromide by an anti-Markovnikov reaction toyield the following compound:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—CH₂—CH₂—Br  (C′).

(D′) (C′) can be converted to a primary alcohol-terminated compound asdiscussed above to yield the following compound:˜˜˜C(CH₃)₂—[CH₂C(CH₃)₂]_(n)—CH₂—CH₂—CH₂—OH  (D′).

As discussed above, in another embodiment the present invention relatesto primary terminated polyisobutylene compounds having two or moreprimary termini selected from an amine groups or methacrylate groups.Again, as in other embodiments of the present invention, the followingembodiments can be applied to linear, star, hyperbranched, orarborescent molecules with the number of repeating units in the PIBportion of such molecules being the same as defined as noted above.

4. Synthesis of Polyisobutylene Methacrylate Macromolecules(PIB-(CH₂)₃-MA)

Synthesis of a primary methacrylate-terminated polyisobutylene iscarried out according to the exemplary reaction scheme shown below:

To 1.0 grams of PIB-(CH₂)₃—Br (M_(n)=5160 grams/mole andM_(w)/M_(n)=1.065) dissolved in 20 mL of THF is added 10.0 mL NMP toincrease the polarity of the medium. To this solution is added 1 gram ofsodium methacrylate, and the mixture is refluxed at 80° C. for 18 hours.The charge is diluted by the addition of 50 mL hexanes and washed 3times with excess water. The organic layer is separated, washed threetimes with distilled water and dried over MgSO₄. The hexanes are removedby a rotavap and the resulting polymer is dried under vacuum, and theyield of PIB-(CH₂)₃-MA is 0.95 grams (95%).

It should be noted that the above embodiment is not limited to just theuse of sodium methacrylate, but rather other suitable methacrylatecompounds could be used. Such compounds include, but are not limited to,alkaline methacrylate compounds.

Additionally, the present invention is not limited to solely the use ofallyl-terminated compounds in the methacrylate-terminatedpolyisobutylene production process disclosed herein. Instead, otherstraight or branched C₃ to C₁₂, C₄ to C₁₀, or even C₅ to C₇ alkenylgroups can be used so long as one double bond in such alkenyl groups ispresent at the end of the chain. Here, as well as elsewhere in thespecification and claims, individual range limits can be combined toform alternative non-disclosed range limits.

As a further example regarding the above-mentioned alkenyl groups thefollowing general formula is used to show the positioning of the enddouble bond:—R₁═CH₂where R₁ is the remaining portion of the straight or branched alkenylgroups described above. In another embodiment, the alkenyl groups of thepresent invention contain only one double bond and this double bond isat the end of the chain as described above.

5. Synthesis of Amine-Terminated Polyisobutylene (PIB-(CH₂)₃—NH₂)

In this embodiment, the synthesis of PIB-(CH₂)₃NH₂ involves two steps:(a) substitution of the terminal primary bromine tophthalimide-terminated polyisobutylene (PIB-(CH₂)₃-phthalimide); and (b)hydrazinolysis of the phthalimide terminated polyisobutylene to primaryamine-terminated polyisobutylene (PIB-(CH₂)₃—NH₂).

(a) Synthesis of Phthalimide-Terminated Polyisobutylene(PIB-(CH₂)₃-Phthalimide)

Synthesis of a phthalimide-terminated polyisobutylene(PIB-(CH₂)₃-phthalimide) is carried out according to the reaction schemeshown below:

To 1.0 gram of PIB-(CH₂)₃—Br (M_(n)=5160 grams/mole andM_(w)/M_(n)=1.06) dissolved in 20 mL THF is added 10 mL of NMP toincrease the polarity of the medium. To this solution is added 1.0 gramof potassium phthalimide and the mixture is refluxed at 80° C. for 4hours. The reaction mixture is diluted by the addition of 50 mL hexanesand washed 3 times with excess water. The organic layer is separated,washed three times with distilled water and dried over MgSO₄. Thehexanes are removed by a rotavap, and the resulting polymer is driedunder vacuum. The yield of PIB-(CH₂)₃-phthalimide is 0.97 grams.

(b) Synthesis of Primary Amine-Terminated Polyisobutylene(PIB-(CH₂)₃—NH₂)

Synthesis of an amine-terminated polyisobutylene (PIB-(CH₂)₃—NH₂) iscarried out according to the reaction scheme shown below:

To 1.0 gram of PIB-(CH₂)₃-phthalimide dissolved in a mixture of 20 mLheptane and 20 mL of ethanol is added 3 grams of hydrazine hydrate. Thismixture is then refluxed at 105° C. for 5 hours. Then the charge isdiluted with 50 mL hexanes and washed 3 times with excess water. Theorganic layer is separated, washed three times with distilled water anddried over MgSO₄. The hexanes are removed by a rotavap and the polymeris dried under vacuum. The yield of PIB-(CH₂)₃—NH₂ is 0.96 grams.

It should be noted that the present invention is not limited to solelythe use of allyl-terminated compounds, shown above, in theamine-terminated polyisobutylene production process disclosed herein.Instead other straight or branched C₃ to C₁₂, C₄ to C₁₀, or even C₅ toC₇ alkenyl groups can be used so long as one double bond in such alkenylgroups is present at the end of the chain. Here, as well as elsewhere inthe specification and claims, individual range limits can be combined toform alternative non-disclosed range limits.

As a further example regarding the above-mentioned alkenyl groups thefollowing general formula is used to show the positioning of the enddouble bond:—R₁═CH₂where R₁ is the remaining portion of the straight or branched alkenylgroups described above. In another embodiment, the alkenyl groups of thepresent invention contain only one double bond and this double bond isat the end of the chain as described above.

In another embodiment, the present invention relates to apolyisobutylenes having at least two primary bromine termini as shown inthe formula below:˜˜˜C(CH₃)₂—[CH₂C(CH₃)₂]_(n)—R₃—Brwhere ˜˜˜ represents the remaining portion of a linear, star,hyperbranched, or arborescent molecule and n is defined as noted above.As would be apparent to those of skill in the art, ˜˜˜ can in someinstances represent another bromine atom in order to permit theproduction of substantially linear di-terminal primary alcohol PIBs. Inthe above formula R₃ represents the remainder of the alkenyl group leftafter subjecting a suitable alkenyl-terminated compound to ananti-Markovnikov bromination step in accordance with the presentinvention. As would be apparent to those of skill in the art R₃ could beeither a straight or branched C₃ to C₁₂, C₄ to C₁₀, or even C₅ to C₇alkyl group (the result of the “starting” alkenyl group having only onedouble bond, with such double bond being present at the end of the chainas described above). In another embodiment, R₃ could be either astraight or branched C₃ to C₁₂, C₄ to C₁₀, or even C₅ to C₇ alkenylgroup (the result of the “starting” alkenyl group having two or moredouble bonds, with one of the double bonds being present at the end ofthe chain as described above).Telechelic Amine and Alcohol PIBs for Use in the Production of VariousPolymer Compounds:

In another embodiment, the present invention relates to amine-telechelicpolyisobutylenes (PIBs) that carry a certain amount of functionalprimary (—NH₂), secondary (—NH—R₄), or tertiary (═N—R₄)amine end groupswhere R₄ is as defined below. In yet another embodiment, the presentinvention relates to alcohol-telechelic PIBs that carry a certain amountof functional primary alcohol end groups (—OH).

The term telechelic (from the Greek telos=far, and chelos=claw)indicates that each and every terminus of a polymer molecule is fittedwith a functional end group. In one embodiment of the present inventionthe functional end groups of the present invention are hydroxyl or amineend groups. In another embodiment of the present invention, each chainend of a hydroxyl- or an amine-telechelic PIB molecule carries about1.0±0.05 functional groups (i.e., a total of about 2.0±0.05, i.e.,better than about 95 mole percent).

As is noted above, in one embodiment the present invention relates toamine-telechelic polyisobutylenes (PIBs) are PIBs that carry primary(—NH₂), secondary (—NH—R₄), or tertiary (═N—R₄)amine end groups, whereR₄ is selected from linear or branched C₁ to C₃₀ alkyl group, a linearor branched C₂ to C₃₀ alkenyl group, a linear or branched C₂ to C₃₀alkynyl group. In another embodiment, R₄ is selected from linear orbranched C₁ to C₂₀ alkyl group, a linear or branched C₂ to C₂₀ alkenylgroup, a linear or branched C₂ to C₂₀ alkynyl group. In still anotherembodiment, R₄ is selected from linear or branched C₁ to C₁₀ alkylgroup, a linear or branched C₂ to C₁₀ alkenyl group, a linear orbranched C₂ to C₁₀ alkynyl group, or even C₁ to C₅ alkyl group, a linearor branched C₂ to C₆ alkenyl group, a linear or branched C₂ to C₆alkynyl group. Here, as well as elsewhere in the specification andclaims, individual range limits can be combined to form alternativenon-disclosed range limits.

In yet another embodiment, R₄ is selected from either a methyl, ethyl,propyl, or butyl group, or even a methyl or ethyl group.

The simplest telechelic PIB molecule is the ditelechelic structure; forexample, a PIB fitted with one —NH₂ group at either end of the molecule:H₂N-PIB-NH₂. A PIB carrying only one —NH₂ terminus (i.e., PIB-NH₂) isnot an amine-telechelic PIB within the definition known to those ofskill in the art. A three-arm star amine-telechelic PIB (i.e., atri-telechelic PIB) carries three —NH₂ groups, one —NH₂ group at eacharm end: abbreviated R₅(PIB-NH₂)₃, where the R₅ is selected from anytri-substituted aromatic group. In another embodiment, in the case of athree-arm star amine-telechelic PIB, R₅ can be any suitable functionalgroup that can be tri-substituted with three PIB-NH₂ groups. Ahyperbranched or arborescent amine-telechelic PIB carries many —NH₂termini, because all the branch ends carry an —NH₂ terminus(multi-telechelic PIB). In another embodiment, the primary —NH₂ groupsmentioned above can be replaced by the afore-mentioned secondary(—NH—R₄), or tertiary (═N—R₄)amine end groups with R₄ being definedabove.

Molecules with less than about 1.0±0.05 hydroxyl or amine groups perchain end, and synthesis methods that yield less than about 1.0±0.05hydroxyl or amine groups per chain end are of little or no practicalinterest in the production of compounds for use in the production ofpolyurethanes and/or polyureas. This stringent requirement must be metbecause these telechelic PI Bs are designed to be used as intermediatesfor the production of polyurethanes and polyureas, and precise startingmaterial stoichiometry is required for the preparation of polyurethaneand/or polyurea compounds having optimum mechanical properties. In theabsence of precise (i.e., about 1.0±0.05) terminal functionality, thepreparation of high quality polyurethanes and polyureas is not possible.

Polymers obtained by the reaction of hydroxy-ditelechelic PIB (i.e.,HO-PIB-OH) and diisocyanates (e.g., MDI) contain urethane (carbamate)linkages:˜˜˜OH+OCN˜˜˜→˜˜˜O—CO—NH˜˜˜and are called polyurethanes, where in this case ˜˜˜ represents theremainder of the polyurethane molecule. Similarly, polymers prepared byamine-ditelechelic PIB (H₂N-PIB-NH₂) plus diisocyanates contain urealinkages:˜˜˜NH₂+OCN˜˜˜→˜˜˜NH—CO—NH˜˜˜and are called polyureas, where in this case ˜˜˜ represents theremainder of the polyurea molecule.

Finally, the overall cost of the products, as determined by the cost ofthe starting materials and the procedures, is of decisive importancebecause only low cost commercially feasible simple syntheses areconsidered.

Although the present invention specifically discloses a method forproducing various alcohol-telechelic PIBs and amine-telechelic PIBsterminated with at least two alcohol or amine groups, the presentinvention is not limited thereto. Rather, the present invention can beused to produce a wide variety of PIB molecular geometries, where suchmolecules are terminated with two or more primary alcohols or two ormore amine groups be they primary amine groups, secondary amine groups,or tertiary amine groups.

In one embodiment, the primary alcohols that can be used as terminatinggroups in the present invention include, but are not limited to, anystraight or branched chain primary alcohol substituent group having from1 to about 12 carbon atoms, or from 1 to about 10 carbon atoms, or from1 to about 8, or from about 1 to about 6 carbon atoms, or even fromabout 2 to about 5 carbon atoms. Here, as well as elsewhere in thespecification and claims, individual range limits can be combined toform alternative non-disclosed range limits.

In another embodiment, the present invention relates to linear, orstar-shaped, or hyperbranched, or arborescent PIB compounds, where suchcompounds contain two or more primary alcohol-terminated segments,amine-terminated segments, or amine-containing segments. Such moleculargeometries are known in the art, and a discussion herein is omitted forthe sake of brevity. In another embodiment, the present inventionrelates to star-shaped molecules that contain a center cyclic group(e.g., an aromatic group) to which three or more primaryalcohol-terminated PIB arms are attached, or three or moreamine-containing PIB arms are attached.

The following examples are exemplary in nature and the present inventionis not limited thereto. Rather, as is noted above, the present inventionrelates to the production and/or manufacture of various primaryalcohol-terminated PIB compounds and polyurethane compounds madetherefrom.

EXAMPLES

The following example concerns the synthesis of a primaryhydroxyl-terminated polyisobutylene in three steps as is discussedabove:

1. Preparation of a Star Molecule with Three Allyl-Terminated PIB Arms(Ø-(PIB-Allyl)₃)

The synthesis of Ø(PIB-Allyl)₃ followed the procedure described by LechWilczek and Joseph P. Kennedy in The Journal of Polymer Science: Part A:Polymer Chemistry, 25, pp. 3255 through 3265 (1987), the disclosure ofwhich is incorporated by reference herein in its entirety.

The first step involves the polymerization of isobutylene totert-chiorine-terminated PIB by the1,3,5-tri(2-methoxyisopropyl)benzene/TiCl₄ system under a blanket of N₂in a dry-box. Next, in a 500 mL three-neck round bottom glass flask,equipped with an overhead stirrer, the following are added: a mixedsolvent (n-hexane/methyl chloride, 60/40 v/v), 2,6-di-t-butyl pyridine(0.007 M), 1,3,5-tri(2-methoxyisopropyl)benzene (0.044M), andisobutylene (2 M) at a temperature of −76° C. Polymerization is inducedby the rapid addition of TiCl₄ (0.15 M) to the stirred charge. After 10minutes of stirring the reaction is terminated by the addition of a 3fold molar excess of allyltrimethylsilane (AllylSiMe₃) relative to thetert-chlorine end groups of the Ø-(PIB-Cl)₃ that formed. After 60minutes of further stirring at 76° C., the system is deactivated byintroducing a few milliliters of aqueous NaHCO₃, and the(allyl-terminated polyisobutylene) product is isolated. The yield is 28grams (85% of theoretical); M_(n)=3000 g/mol.

2. Preparation of Ø(PIB-CH₂—CH₂—CH₂—Br)₃: Anti-Markovnikov Addition ofHBr to Ø(PIB-Allyl)₃

A 100 mL three-neck flask is charged with heptane (50 mL) andallyl-telechelic polyisobutylene (10 grams), and air is bubbled throughthe solution for 30 minutes at 100° C. to activate the allylic endgroups. Then the solution is cooled to approximately −10° C. and HBr gasis bubbled through the system for 10 minutes.

Dry HBr is generated by the reaction of aqueous (47%) hydrogen bromideand sulfuric acid (95 to 98%). After neutralizing the solution withaqueous NaHCO₃ (10%), the product is washed 3 times with water. Finallythe solution is dried over magnesium sulfate for at least 12 hours(i.e., over night) and filtered. The solvent is then removed via arotary evaporator. The product is a clear viscous liquid.

FIG. 1A shows the ¹H NMR spectrum of the allyl-terminated PIB and theprimary bromine-terminated PIB product (FIG. 1B). The formulae and thegroup assignments are indicated below for FIGS. 1A and 1B.

where n is an integer from 2 to about 5,000, or from about 7 to about4,500, or from about 10 to about 4,000, or from about 15 to about 3,500,or from about 25 to about 3,000, or from about 75 to about 2,500, orfrom about 100 to about 2,000, or from about 250 to about 1,500, or evenfrom about 500 to about 1,000. Here, as well as elsewhere in thespecification and claims, individual range limits can be combined toform alternative non-disclosed range limits.

It should be noted that the present invention is not limited to solelythe use of allyl-terminated compounds, shown above, in thealcohol-terminated polyisobutylene production process disclosed herein.Instead, other straight or branched C₃ to C₁₂, C₄ to C₁₀, or even C₅ toC₇ alkenyl groups can be used so long as one double bond in such alkenylgroups is present at the end of the chain. Here, as well as elsewhere inthe specification and claims, individual range limits can be combined toform alternative non-disclosed range limits.

As a further example regarding the above-mentioned alkenyl groups thefollowing general formula is used to show the positioning of the enddouble bond:—R₁═CH₂where R₁ is the remaining portion of the straight or branched alkenylgroups described above. In another embodiment, the alkenyl groups of thepresent invention contain only one double bond and this double bond isat the end of the chain as described above.

The olefinic (allylic) protons at 5 ppm present in spectrum (A)completely disappear upon anti-Markovnikov hydrobromination, as is shownin spectrum (B). The aromatic protons present in the1,3,5-tri(2-methoxyisopropyl)benzene (initiator residue) provide aninternal reference. Thus, integration of the terminal methylene protonsof the -PIB-CH₂—CH₂—CH ₂—Br relative to the three aromatic protons inthe initiator fragment yields quantitative functionality information.The complete absence of allyl groups and/or secondary bromines indicatessubstantially 100% conversion to the target anti-Markovnikov productØ(PIB-CH₂—CH₂—CH₂—Br)₃.

3. Preparation of Ø(PIB-CH₂—CH₂—CH₂—OH)₃ from Ø(PIB-CH₂—CH₂—CH₂—Br)₃

The conversion of the terminal bromine product to a terminal primaryhydroxyl group is performed by nucleophilic substitution on the bromine.A round bottom flask equipped with a stirrer is charged with a solutionof Ø(PIB-CH₂—CH₂—CH₂—Br)₃ in THF. Then an aqueous solution of NaOH isadded, and the charge is stirred for 2 hours at room temperature.Optionally, a phase transfer catalyst such as tetraethyl ammoniumbromide can be added to speed up the reaction. The product is thenwashed 3 times with water, dried over magnesium sulfate overnight andfiltered. Finally the solvent is removed via the use of a rotaryevaporator. The product, a primary alcohol-terminated PIB product, is aclear viscous liquid.

In another embodiment, the present invention relates to a process forproducing halogen-terminated PIBs (e.g., chlorine-terminated PIBs ratherthan the bromine containing compounds discussed above). Thesehalogen-terminated PIBs can also be utilized in above process andconverted to primary alcohol-terminated PIB compounds. Additionally, asis noted above, the present invention relates to the use of such PIBcompounds in the production of polyurethanes, as well as a variety ofother polymeric end products, such as methacrylates (via a reaction withmethacryloyl chloride), hydrophobic adhesives (e.g., cyanoacrylatederivatives), epoxy resins, polyesters, etc.

In still another embodiment, the primary halogen-terminated PIBcompounds of the present invention can be converted into PIB compoundsthat contain end epoxy groups, amine groups, etc. Previous efforts toinexpensively prepare primary halogen-terminated PIB compounds werefruitless and only resulted in compounds with tertiary terminalhalogens.

As noted above, the primary alcohol-terminated PIBs are usefulintermediates in the preparation of polyurethanes by reaction viaconventional techniques, i.e., by the use of known isocyanates (e.g.,4,4′-methylenediphenyl diisocyanate, MDI) and chain extension agents(e.g., 1,4-butane diol, BDO). The great advantage of these polyurethanes(PUs) is their biostability imparted by the biostable PIB segment.Moreover, since PIB is known to be biocompatible, any PU made from thePIB compounds of the present invention is novel as well asbiocompatible.

The primary terminal OH groups can be further derivatized to yieldadditional useful derivatives. For example, they can be converted toterminal cyanoacrylate groups which can be attached to living tissue andin this manner new tissue adhesives can be prepared.

In one embodiment of the present invention, the starting PIB segment canbe mono-, di- tri, and multi-functional, and in this manner one canprepare di-terminal, tri-terminal, or other PIB derivatives. In anotherembodiment, the present invention makes it possible to prepare α,ωdi-terminal (telechelic), tri-terminal, or other PIB derivatives. One ofthe most interesting PIB starting materials is arborescent-PIB (arb-PIB)that can carry many primary halogen termini, all of which can beconverted to primary alcohol groups.

In another embodiment, the following equations describe furtherprocesses and compounds that can be produced via the present invention.As a general rule, all of the following reactions can be run at a 95% orbetter conversion rate.

(A) Cationic living isobutylene polymerization affords a firstintermediate which is, for example, a tert-Cl— terminated PIB chain:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—C(CH₃)₂—Cl  (A)where ˜˜˜ represents the remaining portion of a linear, star,hyperbranched, or arborescent molecule and n is defined as noted above.As would be apparent to those of skill in the art, ˜˜˜ can in someinstances represent another chlorine atom in order to permit theproduction of substantially linear di-terminal primary alcohol PIBs.Additionally, it should be noted that the present invention is notlimited to the above specific linking groups (i.e., the —C(CH₃)₂)between the repeating PIB units and the remainder of the molecules ofthe present invention.

(B) The next step is the dehydrogenation of (A) to afford the secondintermediate shown below:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—C(CH₃)═CH₂  (B).

(C) The third step is the anti-Markovnikov bromination of (B) to affordthe primary bromide shown below:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—CH(CH₃)—CH₂—Br  (C).

(D) The fourth step is the conversion of the primary bromide by the useof a base (e.g., NaOH, KOH, or tert-BuONa) to a primary hydroxyl groupaccording to the following formula:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—CH(CH₃)—CH₂—OH  (D).

In another embodiment, the following reaction steps can be used toproduce a primary alcohol-terminated PIB compound according to thepresent invention.

(B′) Instead of the dehydrogenation, as outlined in (B), one can use anallyl silane such as trimethyl allyl silane to prepare an allylterminated PIB:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—CH═CH₂  (B′).

(C′) Similarly to the reaction shown in (C) above, the (B′) intermediateis converted to the primary bromide by an anti-Markovnikov reaction toyield the following compound:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—CH₂—CH₂Br  (C′).

(D′) (C′) can be converted to a primary alcohol-terminated compound asdiscussed above to yield the following compound:˜˜˜C(CH₃)₂—[CH₂—C(CH₃)₂]_(n)—CH₂—CH₂—CH₂—OH  (D′).

4. The Structure, Synthesis and Characterization of H₂N-PIB-NH₂

The detailed structure of this example, the amine-ditelechelic PIB, isdefined by the following Formula. However, the present invention is notlimited thereto.

where n and m are each independently selected from an integer in therange of from 2 to about 5,000, or from about 7 to about 4,500, or fromabout 10 to about 4,000, or from about 15 to about 3,500, or from about25 to about 3,000, or from about 75 to about 2,500, or from about 100 toabout 2,000, or from about 250 to about 1,500, or even from about 500 toabout 1,000. Here, as well as elsewhere in the specification and claims,individual range limits can be combined to form alternativenon-disclosed range limits.

The above compound can be produced from a corresponding brominatedstructure as shown above in (C). The following chemical equationssummarize the synthesis method for the above compound:

where n and m are each independently selected from an integer in therange of from 2 to about 5,000, or from about 7 to about 4,500, or fromabout 10 to about 4,000, or from about 15 to about 3,500, or from about25 to about 3,000, or from about 75 to about 2,500, or from about 100 toabout 2,000, or from about 250 to about 1,500, or even from about 500 toabout 1,000. Here, as well as elsewhere in the specification and claims,individual range limits can be combined to form alternativenon-disclosed range limits.

Additionally, the reaction conditions at A are: 30 grams of polymer, 150mL of heptane (103 grams), reflux at 110° C. for 30 minutes, followed bypassing HBr over the polymer solutions for 5 minutes at 0° C.

The Allyl-PIB-Allyl is then converted to the telechelic primary bromide,Br—(CH₂)₃-PIB-(CH₂)₃—Br, as described in above. Next, theBr—(CH₂)₃-PIB-(CH₂)₃—Br is converted by using: (1) potassiumphthalimide; and (2) hydrazine hydrate to yield the target ditelechelicamine: NH₂—(CH₂)₃-PIB-(CH₂)₃—NH₂.

Following the above process, 16 grams of bromo-ditelechelicpolyisobutylene (0.003 mol) is dissolved in 320 mL dry THF. Then, 160 mLof NMP and phthalimide potassium (2.2 grams, 0.012 moles) are added tothis solution. Next, the solution is heated to reflux at 80° C. for 8hours. The product is then dissolved in 100 mL of hexanes, extracted 3times with water and dried over magnesium sulfate. The structure of theintermediate is ascertained by ¹H NMR spectroscopy. FIG. 2, below, showsthe ¹H NMR spectrum of phthalimide-telechelic polyisobutylene togetherwith assignments.

Then, the phthalimide-telechelic polyisobutylene (14 grams, 0.0025moles) is dissolved in 280 mL of heptane, then 280 mL of ethanol andhydrazine hydrate (3.2 grams, 0.1 moles) are added thereto, and thesolution is heated to reflux at 110° C. for 6 hours. The product isdissolved in hexanes, extracted 3 times with water, dried over magnesiumsulfate, and the hexanes are removed by a rotavap. The structure of thetarget product is ascertained by ¹H NMR spectroscopy. FIG. 3 shows the¹H NMR spectrum of amine-telechelic polyisobutylene together withassignments.

5. The Synthesis and Characterization of PIB-Based Polyurethanes andPolyureas

(a). Polyurethanes:

(1) The Synthesis of the HO-PIB-OH Starting Material:

The synthesis of HO-PIB-OH is as described above. Thus, the startingmaterial, a commercially available (Kaneka Inc.) allyl-ditelechelic PIB(M_(W)=5,500 g/mol) is hydro-brominated by dissolving it in heptane andbubbling HBr through the solution for 30 minutes at 70° C. Then theproduct is dissolved in THF, aqueous KOH and n-methylpyrrolidone areadded, and the system is refluxed for 24 hours at 100° C. The structureof the HOPIBOH is ascertained by proton NMR spectroscopy.

(2) The Synthesis of a PIB-Based Polyurethane and Demonstration of itsOxidative Stability:

The polyurethane is obtained by reaction of the HOPIBOH withmethylene-bis-phenyl isocyanate (MDI). The following equations describethe synthesis strategy used:

where n and m are each independently selected from an integer in therange of from 2 to about 5,000, or from about 7 to about 4,500, or fromabout 10 to about 4,000, or from about 15 to about 3,500, or from about25 to about 3,000, or from about 75 to about 2,500, or from about 100 toabout 2,000, or from about 250 to about 1,500, or even from about 500 toabout 1,000. Here, as well as elsewhere in the specification and claims,individual range limits can be combined to form alternativenon-disclosed range limits.

Thus, HO-PIB-OH (2.2 grams, M_(n)=5,500 g/mol, hydroxyl equivalent0.0008 mole) is dissolved in dry toluene (12 mL) and freshly distilledMDI (0.3 grams, 0.0012 moles of isocyanate) and tin dioctoate (0.03 mL)catalyst are added under a dry nitrogen atmosphere. The charge is thenheated for 8 hours at 70° C., cooled to room temperature, and poured ina rectangular (5 cm×5 cm) Teflon mold. The system is air dried overnightand finally dried in a drying oven at 70° C. for 24 hours. Thepolyurethane product is a pale yellow supple rubbery sheet, soluble inTHF. Manual examination reveals good mechanical properties.

The oxidative resistance of the polyurethane is tested by placing smallamounts (approximately 0.5 grams) of pre-weighed samples in concentrated(65%) nitric acid in a 25 mL glass vial, and gently agitating the systemat room temperature. Concentrated nitric acid is recognized to be one ofthe most aggressive and corrosive oxidizing agents. After 24 and 48hours the appearance of the samples is examined visually and theirweight loss determined gravimetrically by using the followingexpression:W _(loss)=(W _(b) −W _(a) /W _(b))100where W_(loss) is percent weight loss and W_(b) and W_(a) are theweights of the samples before and after nitric acid exposure,respectively. The weight loss is experimentally determined by removingthe pre-weighed samples from the nitric acid, rinsing them thoroughlywith water, drying them till weight constancy (approximately 24 hours),and weighed again. For comparison, the same procedure is also carriedout with a “control” polyurethane prepared using a HO—PDMS—OH and MDI,and with another commercially available polyurethane (AorTechBiomaterials, Batch #60802, E2A pellets sample).

The control polyurethane is prepared as follows: 1 gram (0.0002 moles)of hydroxy-ditelechelic polydimethylsiloxane (DMS-C21, Gelest,M_(n)=4500-5500 g/mol) is dissolved in 10 mL of toluene, and freshlydistilled MDI (0.11 grams, 0.0002 moles) followed by (0.03 mL) tinoctoate catalyst are added under a dry nitrogen atmosphere. The chargeis heated for 8 hours at 70° C., cooled to room temperature, and pouredin a rectangular (5 cm×5 cm) Teflon mold. The polyurethane sheet that isproduced is air dried overnight and finally dried in a drying oven at70° C. for 24 hours. The product is a pale yellow supple rubbery sheet,soluble in THF. Manual examination reveals good mechanical properties.

Table 1 summarizes the results of aggressive oxidative degradation testperformed with PIB-, PDMS-based polyurethanes and a PIB-based polyurea.The oxidant is 65% HNO₃ at room temperature.

TABLE 1 Time of exposure to Weight concentrated Loss in Materials HNO₃Percent Observations PIB-Based 1 hour 0 No visible change (HO-PIB-OH) 4hours 0 No visible change Polyurethane 24 hours 0 No visible change 48hours 0 Deep brown discoloration, sample becomes weak PDMS-based 30minutes 40 Sample disintegrates to pasty (HO-PDMS-OH) mass adhering toglass Control 2 hours 60 Sample largely dissolved, Polyurethane somediscolored jelly mass remains 4 hours 90 Sample largely dissolved, somediscolored jelly mass remains Commercial 30 minutes 50 Sampledisintegrated, some Polyurethane discolored jelly mass remains (AorTech)1.5 hours 70 Sample disintegrated, some discolored jelly mass remains 4hours 95 Sample disintegrated, some discolored jelly mass remainsPIB-Based 1 hours 0 No visible change (H₂N-PIB-NH₂) 4 hours 0 No visiblechange Polyurea 24 hours 0 No visible change 48 hours 0 Deep browndiscoloration, sample becomes weak

According to the data, the PIB-based polyurethanes and polyureas(prepared with HO-PIB-OH/MDI and H₂N-PIB-NH₂/MDI) do not degrade after24 hours when exposed to concentrated HNO₃ at room temperature.Oxidative resistance is demonstrated by the negligible weight loss ofthe polyurethane and polyurea films. After 48 hours exposure toconcentrated HNO₃ both the PIB-based polyurethane and polyurea filmsexhibit deep brown discoloration and a visible weakening of the samples.In contrast, the control polyurethane prepared with HO—PDMS—OH/MDI, anda commercial polyurethane (i.e., a material considered highlyoxidatively stable) completely degrades, and becomes largely soluble inthe acid after less than 4 hours of exposure.

While not wishing to be bound to any one theory, the spectacularoxidative resistance of the PIB-based polyurethane and polyurethaneformed in accordance with the synthesis processes of the presentinvention is most likely due to the protection of the vulnerableurethane (carbamate) and urea bonds by the inert PIB chains/domains. Incontrast, the PDMS chains/domains cannot impart protection against theattack of the strong oxidizing acid.

(b) Polyureas:

(1) The Synthesis of PIB-Based Polyureas and Demonstration of theirOxidative Stability:

To H₂N-PIB-NH₂ (1.5 grams, M_(n)=5,500 g/mol, amine equivalent 0.00054moles) dissolved in dry toluene (10 mL) is added freshly distilled MDI(0.125 grams, 0.0005 moles), with stirring, under a dry nitrogenatmosphere. Within a minute the solution becomes viscous. It is thendiluted with 5 mL of toluene and poured in a rectangular (5 cm×5 cm)Teflon mold. The system is air dried overnight and finally dried in adrying oven at 70° C. for 24 hours. The polyurea product is a paleyellow supple rubbery sheet, soluble in THF. Manual examination revealsreasonable mechanical properties.

The oxidative stability of the polyurea is tested by exposing the sampleto concentrated HNO₃ at room temperature (see Table 1 above). The lastentry in Table 1 shows data relating to this Example. Evidently, thePIB-based polyurea resists oxidation under the harsh conditions detailedabove for 24 hours.

Although the invention has been described in detail with particularreference to certain embodiments detailed herein, other embodiments canachieve the same results. Variations and modifications of the presentinvention will be obvious to those skilled in the art and the presentinvention is intended to cover in the appended claims all suchmodifications and equivalents.

What is claimed is:
 1. A method for producing a primary amine-terminatedpolyisobutylene compound comprising the steps of: (i) providing anallyl-terminated polyisobutylene having at least two allyl termini,wherein the allyl termini are formed from straight C₃ to C₁₂ allylgroups having a double bond present at the end of the allyl group; (ii)subjecting the allyl-terminated polyisobutylene to anti-Markovnikovbromination to form a primary bromine-terminated polyisobutylenecompound having at least two primary bromine termini; (iii) convertingthe primary bromine-terminated polyisobutylene compound to a primaryphthalimide-terminated polyisobutylene via a reaction with at least onealkaline phthalimide compound, the primary phthalimide-terminatedpolyisobutylene having at least two primary phthalimide termini; (iv)converting the primary phthalimide-terminated polyisobutylene compoundto a primary amine-terminated compound via a reaction with an aminehydrate compound; and (v) recovering the primary amine-terminatedpolyisobutylene.
 2. The method of claim 1, wherein the allyl termini are—CH₂—CH═CH₂.
 3. The method of claim 1, wherein the anti-Markovnikovbromination reaction of Step (ii) utilizes HBr.
 4. The method of claim1, wherein the primary amine-terminated polyisobutylene compound is alinear molecule.
 5. The method of claim 1, wherein the primaryamine-terminated polyisobutylene compound is a star molecule.
 6. Themethod of claim 1, wherein the primary amine-terminated polyisobutylenecompound is a hyperbranched molecule.
 7. The method of claim 1, whereinthe primary amine-terminated polyisobutylene compound is an arborescentmolecule.
 8. The method of claim 1, wherein Step (iv) comprises the useof hydrazine hydrate.